This invention relates to devices for maintaining blood vessels or other body ducts in an open condition, and more particularly to a coil wire stent having selected flex/stiffness orientations.
Vascular medical treatment procedures are known to include, among other things, occluding a blood vessel by thrombogenic devices, and maintaining the blood vessels open by use of a stent. Stents typically used in the past have consisted of a stainless steel tube section which includes selectively positioned gaps or openings which enable the section to be expanded, for example, by a balloon catheter, after the section is positioned at the desired location in the blood vessel. The expansion of the tubular section may be likened in some aspect to the expansion of a molly bolt cartridge in which two ends are drawn together causing the center section to bow outwardly.
Problems with the above prior art stent, among other things, are that the length changes when the tubular section is expanded (the length shortened), and the length of the stent is limited since the longer is the length, the more difficult it is to deliver the stent to a target location in the blood vessel. That is, the stent, being rigid, does not navigate well in the blood vessel, especially around tight corners. Further, since the described stent cannot be very long, numerous stents must be used for a diffuse diseased blood vessel.